Alexis Poignant
Postdoc
Email: alexis.poignant@ijs.si
Education
Phd Robotics, Sorbonne University, France (2024)
Post-Master in AI applied to human-motion, Mines Paristech, France (2020)
MSc Control Engineer, CentraleSupélec, France (2019)
Research interests
- Assistive Robotics
- Wearable Robotics
- Human-Robot Interaction
Selected Publications
Poignant, Alexis; Morel, Guillaume; Jarrassé, Nathanaël
A Comparative Study Between a Virtual Wand and a One-to-One Approach for the Teleoperation of a Nearby Robotic Manipulator Proceedings Article
In: 2025 IEEE International Conference on Robotics and Automation (ICRA), pp. 5608-5614, 2025.
@inproceedings{11127740,
title = {A Comparative Study Between a Virtual Wand and a One-to-One Approach for the Teleoperation of a Nearby Robotic Manipulator},
author = {Alexis Poignant and Guillaume Morel and Nathana\"{e}l Jarrass\'{e}},
doi = {10.1109/ICRA55743.2025.11127740},
year = {2025},
date = {2025-05-01},
urldate = {2025-05-01},
booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},
pages = {5608-5614},
abstract = {The prevailing and most effective approach to teleoperate a robotic arm involves a direct position-to-position mapping, imposing robotic end-effector movements that mirrors those of the user, Fig. 1-top. However, due to this one-to-one mapping, the robot\'s motions are limited by the user\'s capability, particularly in translation. Drawing inspiration from head pointers utilized in the 1980s, originally designed to enable drawing with limited head motions for tetraplegic individuals, we proposed a “virtual wand” mapping which could be used by participants with reduced mobility. This mapping employs a virtual rigid linkage between the hand and the robot\'s endeffector, Fig. 1-bottom. With this approach, rotations produce amplified translations through a lever arm, creating a “rotation-to-position” coupling and expanding the translation workspace at the expense of a reduced rotation space. In this study, we compare the virtual wand approach to the one-to-one position mapping through the realization of 6-DoF reaching tasks. Results indicate that the two different mappings perform comparably well, are equally well-received by users, and exhibit similar motor control behaviors. Nevertheless, the virtual wand mapping is anticipated to outperform in tasks characterized by large translations and minimal effector rotations, whereas direct mapping is expected to demonstrate advantages in large rotations with minimal translations. These results pave the way for new interactions and interfaces, particularly in disability assistance utilizing residual body movements (instead of hands) as control input. Leveraging body parts with substantial rotations could enable the accomplishment of tasks previously deemed infeasible with standard direct coupling interfaces.},
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The prevailing and most effective approach to teleoperate a robotic arm involves a direct position-to-position mapping, imposing robotic end-effector movements that mirrors those of the user, Fig. 1-top. However, due to this one-to-one mapping, the robot's motions are limited by the user's capability, particularly in translation. Drawing inspiration from head pointers utilized in the 1980s, originally designed to enable drawing with limited head motions for tetraplegic individuals, we proposed a “virtual wand” mapping which could be used by participants with reduced mobility. This mapping employs a virtual rigid linkage between the hand and the robot's endeffector, Fig. 1-bottom. With this approach, rotations produce amplified translations through a lever arm, creating a “rotation-to-position” coupling and expanding the translation workspace at the expense of a reduced rotation space. In this study, we compare the virtual wand approach to the one-to-one position mapping through the realization of 6-DoF reaching tasks. Results indicate that the two different mappings perform comparably well, are equally well-received by users, and exhibit similar motor control behaviors. Nevertheless, the virtual wand mapping is anticipated to outperform in tasks characterized by large translations and minimal effector rotations, whereas direct mapping is expected to demonstrate advantages in large rotations with minimal translations. These results pave the way for new interactions and interfaces, particularly in disability assistance utilizing residual body movements (instead of hands) as control input. Leveraging body parts with substantial rotations could enable the accomplishment of tasks previously deemed infeasible with standard direct coupling interfaces.
Poignant, Alexis; Jarrassé, Nathanaël; Morel, Guillaume
Teleoperating a 6 DoF Robotic Manipulator from Head Movements Proceedings Article
In: 2025 IEEE International Conference on Robotics and Automation (ICRA), pp. 1-8, 2025.
@inproceedings{11127494,
title = {Teleoperating a 6 DoF Robotic Manipulator from Head Movements},
author = {Alexis Poignant and Nathana\"{e}l Jarrass\'{e} and Guillaume Morel},
doi = {10.1109/ICRA55743.2025.11127494},
year = {2025},
date = {2025-05-01},
urldate = {2025-05-01},
booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},
pages = {1-8},
abstract = {This article presents an interactive control approach allowing a human user to teleoperate a robotic manipulator located nearby. With this approach, the user keeps his/her hands free, as only head movements are exploited to control the robot. The controller maps the 6 Degrees of Freedom (DoF) user\'s head position and orientation into the 6 DoF robot endeffector position and orientation. The robot can reach a large workspace thanks to the combination of two features. Firstly, a virtual wand between the user\'s head and the robot end-effector converts user\'s head pantilt rotations into large displacements of the robot end-effector center perpendicularly to the wand axis (2 DoF). Secondly, for the remaining 4 DoF (robot end-effector center displacement along the wand axis and robot en-effector orientation), realtime deformation of the virtual wand is triggered when the user reaches uncomfortable configurations due to his/her head workspace limitations. Additionally, the user gets, through an Augmented Reality (AR) Headset, a non-delayed visual feedback of the current virtual wand geometry and location. The paper includes a description of the setup and the proposed controller, detailing how the robot position/orientation is coupled to the user\'s head position/orientation. A set of elementary experiments with a constant-geometry wand is first presented, showing workspace limitations for some DoF. Then the wand reconfiguration is introduced in the experiments, leading to full control of 6 DoF manipulation tasks throughout a large workspace.},
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This article presents an interactive control approach allowing a human user to teleoperate a robotic manipulator located nearby. With this approach, the user keeps his/her hands free, as only head movements are exploited to control the robot. The controller maps the 6 Degrees of Freedom (DoF) user's head position and orientation into the 6 DoF robot endeffector position and orientation. The robot can reach a large workspace thanks to the combination of two features. Firstly, a virtual wand between the user's head and the robot end-effector converts user's head pantilt rotations into large displacements of the robot end-effector center perpendicularly to the wand axis (2 DoF). Secondly, for the remaining 4 DoF (robot end-effector center displacement along the wand axis and robot en-effector orientation), realtime deformation of the virtual wand is triggered when the user reaches uncomfortable configurations due to his/her head workspace limitations. Additionally, the user gets, through an Augmented Reality (AR) Headset, a non-delayed visual feedback of the current virtual wand geometry and location. The paper includes a description of the setup and the proposed controller, detailing how the robot position/orientation is coupled to the user's head position/orientation. A set of elementary experiments with a constant-geometry wand is first presented, showing workspace limitations for some DoF. Then the wand reconfiguration is introduced in the experiments, leading to full control of 6 DoF manipulation tasks throughout a large workspace.
Eden, Jonathan; Khoramshahi, Mahdi; Huang, Yanpei; Poignant, Alexis; Burdet, Etienne; Jarrassé, Nathanaël
Comparison of Solo and Collaborative Trimanual Operation of a Supernumerary Limb in Tasks With Varying Physical Coupling Journal Article
In: IEEE Robotics and Automation Letters, vol. 10, no. 2, pp. 860-867, 2025, ISSN: 2377-3766.
@article{10792937,
title = {Comparison of Solo and Collaborative Trimanual Operation of a Supernumerary Limb in Tasks With Varying Physical Coupling},
author = {Jonathan Eden and Mahdi Khoramshahi and Yanpei Huang and Alexis Poignant and Etienne Burdet and Nathana\"{e}l Jarrass\'{e}},
doi = {10.1109/LRA.2024.3515734},
issn = {2377-3766},
year = {2025},
date = {2025-02-01},
urldate = {2025-02-01},
journal = {IEEE Robotics and Automation Letters},
volume = {10},
number = {2},
pages = {860-867},
abstract = {Through the use of robotic supernumerary limbs, it has been proposed that a single user could perform tasks like surgery or industrial assembly that currently require a team. Although validation studies, often conducted in virtual reality, have demonstrated that individuals can learn to command supernumerary limbs, comparisons typically suggest that a team initially outperforms a supernumerary limb operating individual. In this study, we examined (i) the impact of using a commercially available physical robot setup instead of a virtual reality system and (ii) the effect of limb couplings on user performance during a series of trimanual operations. Contrary to previous findings, our results indicate no clear difference in user performance when working as a trimanual user, in the pick and place of three objects, compared to when working as a team. Additionally, for this task we observe that while users prefer working with a partner when they control most limbs, we find no clear difference in their preference between solo trimanual operation and when they work with a partner and control the third limb. These findings indicate that factors typically not present in virtual reality such as visual occlusion and haptic feedback may be vital to consider for the effective operation of supernumerary limbs, and provide initial evidence to support the viability of supernumerary limbs for a range of physical tasks.},
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Through the use of robotic supernumerary limbs, it has been proposed that a single user could perform tasks like surgery or industrial assembly that currently require a team. Although validation studies, often conducted in virtual reality, have demonstrated that individuals can learn to command supernumerary limbs, comparisons typically suggest that a team initially outperforms a supernumerary limb operating individual. In this study, we examined (i) the impact of using a commercially available physical robot setup instead of a virtual reality system and (ii) the effect of limb couplings on user performance during a series of trimanual operations. Contrary to previous findings, our results indicate no clear difference in user performance when working as a trimanual user, in the pick and place of three objects, compared to when working as a team. Additionally, for this task we observe that while users prefer working with a partner when they control most limbs, we find no clear difference in their preference between solo trimanual operation and when they work with a partner and control the third limb. These findings indicate that factors typically not present in virtual reality such as visual occlusion and haptic feedback may be vital to consider for the effective operation of supernumerary limbs, and provide initial evidence to support the viability of supernumerary limbs for a range of physical tasks.
Poignant, Alexis; Jarrassé, Nathanaël; Morel, Guillaume
Hands-Free Teleoperation of a Nearby Manipulator Through a Virtual Body-to-Robot Link Proceedings Article
In: 2024 10th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob), pp. 619-626, 2024, ISSN: 2155-1782.
@inproceedings{10719920,
title = {Hands-Free Teleoperation of a Nearby Manipulator Through a Virtual Body-to-Robot Link},
author = {Alexis Poignant and Nathana\"{e}l Jarrass\'{e} and Guillaume Morel},
doi = {10.1109/BioRob60516.2024.10719920},
issn = {2155-1782},
year = {2024},
date = {2024-09-01},
urldate = {2024-09-01},
booktitle = {2024 10th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob)},
pages = {619-626},
abstract = {This paper introduces an innovative control approach for teleoperating a robot in close proximity to a human operator, which could be useful to control robots embedded on wheelchairs. The method entails establishing a virtual connection between a specific body part and the robot\'s end-effector, visually displayed through an Augmented Reality (AR) headset. This linkage enables the transformation of body rotations into amplified effector translations, extending the robot\'s workspace beyond the capabilities of direct one-to-one mapping. Moreover, the linkage can be reconfigured using a joystick, resulting in a hybrid position/velocity control mode using the body/joystick motions respectively. After providing a comprehensive overview of the control methodology, we present the results of an experimental cam-paign designed to elucidate the advantages and drawbacks of our approach compared to the conventional joystick-based tele-operation method. The body-link control demonstrates slightly faster task completion and is naturally preferred over joystick velocity control, albeit being more physically demanding for tasks with a large range. The hybrid mode, where participants could simultaneously utilize both modes, emerges as a compro-mise, combining the intuitiveness of the body mode with the extensive task range of the velocity mode. Finally, we provide preliminary observations on potential assistive applications using head motions, especially for operators with limited range of motion in their bodies.},
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pubstate = {published},
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This paper introduces an innovative control approach for teleoperating a robot in close proximity to a human operator, which could be useful to control robots embedded on wheelchairs. The method entails establishing a virtual connection between a specific body part and the robot's end-effector, visually displayed through an Augmented Reality (AR) headset. This linkage enables the transformation of body rotations into amplified effector translations, extending the robot's workspace beyond the capabilities of direct one-to-one mapping. Moreover, the linkage can be reconfigured using a joystick, resulting in a hybrid position/velocity control mode using the body/joystick motions respectively. After providing a comprehensive overview of the control methodology, we present the results of an experimental cam-paign designed to elucidate the advantages and drawbacks of our approach compared to the conventional joystick-based tele-operation method. The body-link control demonstrates slightly faster task completion and is naturally preferred over joystick velocity control, albeit being more physically demanding for tasks with a large range. The hybrid mode, where participants could simultaneously utilize both modes, emerges as a compro-mise, combining the intuitiveness of the body mode with the extensive task range of the velocity mode. Finally, we provide preliminary observations on potential assistive applications using head motions, especially for operators with limited range of motion in their bodies.
Khoramshahi, Mahdi; Poignant, Alexis; Morel, Guillaume; Jarrassé, Nathanael
A Practical Control Approach for Safe Collaborative Supernumerary Robotic Arms Proceedings Article
In: 2023 IEEE International Conference on Advanced Robotics and Its Social Impacts (ARSO), pp. 147-152, 2023, ISSN: 2162-7576.
@inproceedings{10187452,
title = {A Practical Control Approach for Safe Collaborative Supernumerary Robotic Arms},
author = {Mahdi Khoramshahi and Alexis Poignant and Guillaume Morel and Nathanael Jarrass\'{e}},
doi = {10.1109/ARSO56563.2023.10187452},
issn = {2162-7576},
year = {2023},
date = {2023-06-01},
urldate = {2023-06-01},
booktitle = {2023 IEEE International Conference on Advanced Robotics and Its Social Impacts (ARSO)},
pages = {147-152},
abstract = {Supernumerary robotic arms have a high potential to increase human capacities to perform complicated tasks; e.g., having a third arm could increase the user\'s strength, precision, reachability, and versatility. However, having a robotic manipulator working in extreme proximity to the user raises new challenges in terms of safety; i.e., uncontrolled and hazardous collisions with the user\'s body parts and the environment. In this preliminary work, we show that most of these safety considerations can be extracted from standardized norms and translated into kinematics constraints for the robot. Thus, we propose a quadratic programming approach to achieve safe inverse-kinematics and physical interaction for supernumerary arms. We validate our approach in designing a safe supernumerary arm using the 7-Dof Kinova® Gen3 robot.},
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pubstate = {published},
tppubtype = {inproceedings}
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Supernumerary robotic arms have a high potential to increase human capacities to perform complicated tasks; e.g., having a third arm could increase the user's strength, precision, reachability, and versatility. However, having a robotic manipulator working in extreme proximity to the user raises new challenges in terms of safety; i.e., uncontrolled and hazardous collisions with the user's body parts and the environment. In this preliminary work, we show that most of these safety considerations can be extracted from standardized norms and translated into kinematics constraints for the robot. Thus, we propose a quadratic programming approach to achieve safe inverse-kinematics and physical interaction for supernumerary arms. We validate our approach in designing a safe supernumerary arm using the 7-Dof Kinova® Gen3 robot.
Poignant, Alexis; Legrand, Mathilde; Jarrassé, Nathanaël; Morel, Guillaume
Computing the positioning error of an upper-arm robotic prosthesis from the observation of its wearer’s posture Proceedings Article
In: 2021 IEEE International Conference on Robotics and Automation (ICRA), pp. 10446-10452, 2021, ISSN: 2577-087X.
@inproceedings{9561613,
title = {Computing the positioning error of an upper-arm robotic prosthesis from the observation of its wearer’s posture},
author = {Alexis Poignant and Mathilde Legrand and Nathana\"{e}l Jarrass\'{e} and Guillaume Morel},
doi = {10.1109/ICRA48506.2021.9561613},
issn = {2577-087X},
year = {2021},
date = {2021-05-01},
urldate = {2021-05-01},
booktitle = {2021 IEEE International Conference on Robotics and Automation (ICRA)},
pages = {10446-10452},
abstract = {When the arm prosthesis worn by an amputated Human being is not adequately configured with respect to the end-effector task, body compensations are often observed. Namely, to compensate for a wrong joint positioning on the robotic distal side, a subject trying to reach a desired position/orientation of his/her hand mobilizes his/her proximal joints, thus exploiting the redundancy of the human+robot kinematic chain.In this paper, we explore the possibility of exploiting this well-known behavior to reverse the causality: if we observe the posture of an amputated subject wearing a prosthesis during a hand positioning task, to what extent can we infer the positioning error of the prosthesis?To answer this question, we make the assumption that the adequate, or natural posture for a given task is one that optimizes a postural score. The proposed approach then consists in i) measuring the joint posture of the subject fitted with the prosthesis; ii) search for an alternative posture that optimizes a postural score within the null space of the human+robot kinematic chain and iii) compute the position error for the robot joints between the initial and the optimized posture.An experimental evaluation is provided with non amputated subjects who emulate erratic positioning of their distal joints during hand positioning tasks. Results show that joint errors are estimated with a precision that seems compatible with the implementation of a real time control algorithm.},
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pubstate = {published},
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When the arm prosthesis worn by an amputated Human being is not adequately configured with respect to the end-effector task, body compensations are often observed. Namely, to compensate for a wrong joint positioning on the robotic distal side, a subject trying to reach a desired position/orientation of his/her hand mobilizes his/her proximal joints, thus exploiting the redundancy of the human+robot kinematic chain.In this paper, we explore the possibility of exploiting this well-known behavior to reverse the causality: if we observe the posture of an amputated subject wearing a prosthesis during a hand positioning task, to what extent can we infer the positioning error of the prosthesis?To answer this question, we make the assumption that the adequate, or natural posture for a given task is one that optimizes a postural score. The proposed approach then consists in i) measuring the joint posture of the subject fitted with the prosthesis; ii) search for an alternative posture that optimizes a postural score within the null space of the human+robot kinematic chain and iii) compute the position error for the robot joints between the initial and the optimized posture.An experimental evaluation is provided with non amputated subjects who emulate erratic positioning of their distal joints during hand positioning tasks. Results show that joint errors are estimated with a precision that seems compatible with the implementation of a real time control algorithm.